PT1.4 - Testing the bridge

4.1 Testing

The bridge could hold up to 20kg before it started to bend. Therefore, we stopped the test and unloaded the weights from it.

4.2 Calculation of efficiency

(a) Mass of load on bridge =

20

kilogram

(b) Mass of bridge =

0.27

kilogram

Efficiency = (a) / (b)

74

No units

4.3 Discussion of bridge design after testing

Q1. What is your score on efficiency? If the efficiency is high/low, what went right/wrong?

A1. The score on our efficiency was 74 which we considered low . The truss of the bridge bent outwards because we had not reinforced it enough. Since the sides constituted of only two ice cream sticks that sandwiched the joints for the sole purpose of reinforcing strength in the joints ( bad foresight on joints splitting apart ) , the sides of the truss hence bent outwards.

Q2. Which part of the bridge started to give way first? Explain using Physics concepts.
A2. The truss of the bridge. Since the centre of the truss had been reinforced with an x shape which evenly distributes the weight to the segments beside the center, those segments could not take the weight but were glued firmly together. Thus, since the force could not go left or right, the ice cream sticks of the segments bent outwards instead.

Q3. Which part of the bridge provided the most strength in the testing process? Explain using Physics concepts.

A3. The part that provided the most strength was the center region which evenly distributed the mass of the load to the sides of the bridge. Not only did the center portion have an x in a square that consists of 4 triangles (strong shape triangle) but we also bridged the two trusses of the bridge together via the center portion by glueing popsicle sticks in between from on truss to the other.